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SUMMARY:Filling in the Map: Understanding Arctic Ocean mixing rates\, mech
 anisms and space-time geography from ocean observations - Stephanie Waterm
 an\, Department of Earth\, Ocean &amp\; Atmospheric Sciences\, University 
 of British Columbia
DTSTART:20230123T130000Z
DTEND:20230123T140000Z
UID:TALK196048@talks.cam.ac.uk
CONTACT:Prof. John R. Taylor
DESCRIPTION:The rates and mechanisms of ocean mixing are important control
 s on how the oceans function\; yet\, our understanding of mixing in the oc
 ean is significantly limited by complex variability in mixing rates and pr
 ocesses\, and by a scarcity of direct observations. In the Arctic Ocean\, 
 the challenges of understanding ocean mixing are significant: mixing measu
 rements are especially sparse\, and latitude\, ice\, and stratification ma
 ke the mixing environment unique.\n\nIn this talk\, I’ll discuss our gro
 up’s work that uses a variety of pan-Arctic observations and observation
 al methods to better understand Arctic Ocean mixing rates\, mechanisms\, a
 nd space-time geography. Specifically\, I will consolidate results from di
 fferent studies to provide statistical characterizations of Arctic Ocean m
 ixing rate and mixing flux distributions in time and space over a range of
  scales\, as well as insights into the mechanisms driving and/or modulatin
 g the observed mixing space-time geography.\n\nOur results show that turbu
 lence and mixing in the Arctic Ocean is highly variable in space and time 
 over a large range of scales\; despite this\, there are large-scale spatia
 l and temporal patterns that relate to forcing fields. They also show that
  in the ocean interior\, stratification typically inhibits turbulent overt
 urning\, but rare cases where and when it does not can be dominant in sett
 ing net mixing fluxes. Finally\, they suggest that mixing fluxes in the ce
 ntral Arctic have increased over the past two decades\, underpinned by str
 onger and more prevalent internal wave-driven mixing in summer in more rec
 ent years.\n\nI will use this opportunity to also present some thought-pro
 voking observations in attempts to enlist the interest of observationalist
 s and theoreticians alike. First\, I’ll show that turbulence in the Arct
 ic Ocean interior appears to frequently be in a buoyancy-controlled regime
 \, thus requiring an appropriate mixing efficiency to translate turbulent 
 dissipation to diapycnal diffusivity. Next\, I’ll show that in laminar a
 nd very weakly turbulent conditions in the Arctic halocline\, the mixing o
 f heat can be significantly enhanced above theoretical expectations. Final
 ly\, I’ll suggest that the prevalence of different mixing processes sets
  the dominant large-scale patterns of the pan-Arctic map of average effect
 ive diffusivity\, with the competing stabilizing vs. destabilizing effects
  of double-diffusive vs. turbulent mixing processes potentially being an i
 mportant control on stratification in the Arctic Ocean interior.
LOCATION:MR5\, CMS
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